User`s manual

Table Of Contents
Both were taken at-10dBu, a value that gained our favor before. Results are in
Fig.13.6 for MLS and Fig .13.7 for Sinusoidal.
Audiomatica Srl MLS - Frequency Response 03/07/2001 16.35.18
CH A Ohm Unsmoothed 51.2kHz 16K Rectangular File: noise-10.mlsi
100 1k 10k 20k20 Hz
25.0
Ohm
180.0
Deg
20.0 108.0
15.0 36.0
10.0 -36.0
5.0 -108.0
0.0 -180.0
CL IO
Audi omatica Srl Sinusoidal 03/07/2001 16.34.16
CH A Ohm Unsmoothed Stepped Delay [ms]: 0.000 Dist Rise [dB ]: 30.00 Fi le: noise-10.si ni
10 100 1k 10k 20 k10 Hz
25.0
Ohm
180.0
Deg
20.0 10 8.0
15.0 36 .0
10.0 -36.0
5.0 -1 08.0
0.0 -1 80.0
CL IO
Figures 13.6 and 13.7
This is one reason why we prefer sinusoidal analysis to measure impedance.
13.3.4 DEALING WITH VIBRATIONS
The last enemy we must consider is external vibrations.
Audiomatica Srl Sinusoidal 03/07/2001 16.47.17
CH A Ohm Unsmoothed Stepped Delay [ms]: 0.000 Dist Rise [dB]: 30.00 File: vibration.sini
10 100 1k 10k 20k10 Hz
25.0
Ohm
180.0
Deg
20.0 108.0
15.0 36.0
10.0 -36.0
5.0 -108.0
0.0 -180.0
CL IO
Figure 13.8
Fig.13.8 is an impedance curve taken with the loudspeaker positioned on a
computer table, on one of those appendages that may be set up or down upon
needs. This support clearly resonates, exited by the loudspeaker, at around 200Hz.
No matter how good the loudspeaker is fixed to a structure if the structure itself
moves then potential problems may become apparent. Usually there is no need to
fix anything as long as you are using a stable, non-resonating structure.
Up to now we have dealt with Internal Mode. We will briefly go through the others
modes; problems found up to here will remain the same or worsen from here on!
13 MEASURING IMPEDANCE AND T&S PARAMETERS 185